1. Field of the Invention
The present invention relates generally to marine towing devices. In particular, the present invention relates to a connector system by which several barges may be held together in open seas.
2. Description of the Prior Art
Deployable port facilities needed to support both the military's fleet operations and their forces ashore may include large modular facilities mounted on floating barges arranged in close coupled connection. The barge modules are approximately 100 feet wide by 300 feet long and weigh approximately 5000 tons. Module or barge connectors are essential components of these deployable port facilities.
When anchored in a fixed location offshore the connecting arrangement that holds adjacent barges together must be flexible to minimize the forces exerted on the barges and at the same time allow for close coupled connection of the barges with acceptable relative motion for ease of movement of military personnel and equipment on the deployable port facility.
There is also a requirement that the connecting arrangement allow for towing of barges at sea so that the deployable port facility can be moved from location to location. In the past, when one vessel pushed another, for example, when a tug pushed one or more barges, it has been a common practice to interconnect the vessels by rigid structural members in a close-coupled linkage. In inland waterways where maneuverability is important and the water is calm, the use of rigid structural members to connect barges for towing is acceptable although the structural connecting members have been subject to failure because of the stresses caused during towing. In addition, the use of rigid structural members for close-coupled linkage limits control over the barges and the ability to restore the barges to an equilibrium position.
On the open sea, where maneuverability of the barges is not important and sea generated motions are often very large, the tug is often connected to the first barge in a train of barges with relatively long tow lines with the remaining barges in the train being connected together by additional tow lines. Long tow lines are required for shock absorption between the tug and first barge and between successive barges.
However, the use of multiple long tow lines present many disadvantages because the tow lines tend to become fouled and a considerable amount of effort is required to link each tow line to the tug and barges. Also these tow lines create a drag and provide limited capacity for controlling and maneuvering one or more barges at sea.
Accordingly, there is need for an improved connecting arrangement to connect adjacent barges of a deployable port facility anchored at a fixed location and allow for close-coupled ocean towing of large barges which would provide improved control over the towed barges. Such a connecting arrangement should be able to provide control in either a push-tow or a pull-tow situation and be adaptable to towing multiple barges in linear flotilla without the long intermediate tow lines that characterized prior art connecting arrangements. The connecting arrangement should permit relative motions between the barges, including pitch, roll, yaw, sway, surge, and heave while providing yaw, surge, and sway restraining and restoring forces without causing excessive lateral forces.